Long-lived clams reveal secrets of oceans past

Ancient molluscs tell a 1,000-year-old story of our planet's climate

6th December 2016
Long-lived clams reveal secrets of oceans past © Getty

It seems an unlikely connection, but new research has shown that the quahog clam, the longest-living animal on Earth, could be key to piecing together the history of our oceans.

The quahog clam, also known as the hard clam or chowder clam, is a mollusc that can live for over 500 years. Much like the rings of a tree, the growth rings within the clam’s shell can be used to determine its age, as well as provide information about the chemistry of the oceans it grew in.

Prior to this study, instrumental records of the ocean and its effect on the atmosphere were limited to the past 100 years or so. But through chemical analysis of the clams' rings, an international team of scientists has been able to study changes in the North Atlantic Ocean over the past 1,000 years.

Their results show that before the industrial period (pre 1800), changes in the North Atlantic Ocean were driven by variations in the Sun’s activity and volcanic eruptions, which in turn affected the atmosphere and our weather. However, from 1800, changes in the ocean have tended to lag behind changes in the atmosphere, which the researchers say might be due to increased greenhouse gases and global warming.

“These data provide an invaluable archive of the natural state of the ocean system and the expression of anthropogenic change over the last 1000 years,” says Prof Ian Hall at Cardiff University, co-author of the study.

No one knows for sure how the oceans will change in the coming years, but the scientists hope that by looking into the past, they’ll be able to better predict our planet’s future climate.

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